With continued developments in the cosmetic industry, highly functional cosmetics have been continuously developed using new materials and technologies. In addition, in recent years, the amount of consumers who demand specific effects including skin whitening, wrinkle reduction and skin regeneration has increased, and as such the value of functional cosmetics in the cosmetic industry has further increased, and studies on the application of various materials to cosmetics have received attention.
For example, skin wrinkles can be said to be morphological and structural changes in the skin, which occur locally in regions that undergo permanent deformation due to muscular motion. In order to understand the wrinkle formation mechanism, it is important to investigate not only such physiological changes, but also changes in the internal structure and physical properties of the skin. In connection with this, reported changes in the internal structure of the skin, which are caused by photoaging, include thickening of the epidermis and dermis, abnormal accumulation of elastotic material, and changes in the three-dimensional structure of elastic fiber. In addition, with respect to collagen, which is the major component of skin, microfibrillation of collagen fibers, weakening of fibers, and the like have been reported.
Collagen is a major matrix protein that is produced in skin fibroblasts. It is an important protein that is present in the extracellular matrix and accounts for 30 wt % of the total weight of the proteins in the body. It also has a rigid triple-helical structure. It is known that collagen mainly functions to give mechanical firmness to the skin, strengthen connective tissue, bind tissues, maintain cell adhesion, and induce cell division and differentiation (during organism growth or wound healing). The amount of collagen proteins decreases with age and with UV-induced photoaging. As is generally known in the art, as aging progresses, the skin becomes thinner, and this phenomenon is closely associated with a decrease in skin elasticity and the formation of wrinkles.
Active ingredients known to exhibit wrinkle reduction effects by promoting collagen synthesis include, for example, retinoic acid, TGF (transforming growth factor), animal placenta-derived protein (Japanese Patent Laid-Open Publication No. 1996-231370), betulinic acid (Japanese Patent Laid-Open Publication No. 1996-208424), chlorella extracts (Japanese Patent Laid-Open Publication Nos. 1994-040523 and 1998-036283) and the like. However, these active ingredients have a problem in that they may cause side effects, such as irritation and redness, upon application to the skin and thus have had limited applications. Alternatively, these active ingredients have insignificant effects, and thus cannot provide a sufficient effect of improving skin conditions by promoting collagen synthesis in the skin.
It is known that this problem is mainly because the various active ingredients intended to exhibit wrinkle reduction effects by promoting collagen synthesis are not normally absorbed into the skin. Thus, studies have been actively conducted to develop methods for promoting the absorption of the above-described active ingredients. For example, Korean Patent Registration No. 1054519 discloses a human growth hormone-derived peptide having excellent stability and skin penetration properties compared to natural human growth hormones, and a composition comprising the same, and Korean Patent Registration No. 1104223 discloses an IL-10-derived peptide, which performs the same function as that of human IL-10 and has very excellent stability and skin penetration properties compared to natural IL-10, and a composition comprising the same. However, these peptides have a disadvantage in that they merely exhibit functionality by themselves and cannot be used as carriers for delivering other drugs. This disadvantage suggests that excellent skin penetration alone does not satisfy the requirements for drug delivery. Thus, in order to promote collagen synthesis, it is required to develop novel materials that satisfy two requirements: excellent skin penetration, and enhancement of collagen synthesis in the skin. However, the results of dedicated studies on such materials have not yet been reported.